Fast diesel 5-series 'confirmed'

Details leaked from a dealer conference held in Holland this week suggest BMW’s upcoming 550dX, revealed by Autocar back in early September, will be the first recipient of the German car maker’s new tri-turbo 3.0-litre in-line six-cylinder diesel engine.

The new engine, which is also destined for new X5xDrive550d and X6xDrive550d models, is claimed to produce 376bhp and over 516lb ft of torque – some 70bhp and over 74lb ft more than the most powerful version of BMW’s existing twin-turbocharged 3.0-litre in-line six-cylinder diesel engine.

The radical new engine, which is rumoured to use two traditional exhaust blown turbochargers in combination with an electrically driven turbocharger to added low-end response, is planned to be offered exclusively with and eight speed automatic gearbox and four-wheel drive.

The 550dX will slot into the BMW line-up above the 535d. Nothing is official just yet, but Munich insiders hint at 0-62mph acceleration in around 5.0sec and a top speed limited to 155mph. This, with combined cycle fuel consumption that is said to come close to matching the 535d’s 46mpg and 165g/km average CO2 emission rating.

Along with the standard version of the 550dX, BMW is also planning a performance-oriented M550dX. While not an official M model, it will receive various chassis and styling tweaks, according to highly placed BMW sources.

Original plans for a full blown M5 diesel were ditched on grounds that the 550dX’s four-wheel drive system would have dictated the ride height. “There are specific reasons why we didn’t go with four-wheel drive, one of them being the four-wheel drive system that requires the car to ride higher than existing M models,” said an insider.